The present invention relates to a method and apparatus for segregating or separating selected rod-shaped articles from a series of rapidly moving articles, particularly for segregating tobacco-containing plain or filter-tipped rod-shaped articles or sections of filter rods while such articles or sections move sideways. For example, the method and apparatus of the present invention can be utilized to segregate defective rod-shaped tobacco-containing articles or defective sections of filter rods from a row of such articles or sections wherein the defective articles or sections are in random distribution with satisfactory articles or sections.
In the manufacture of cigarettes, cigars, cigarillos, filter rod sections and analogous rod-shaped articles which are used in the manufacture of or constitute smokers' products, the articles are tested at one or more stations to segregate from satisfactory articles those articles which exhibit one or more defects, for example, to segregate sections of a wrapped tobacco filler rod or filter rod if such sections exhibit a leak (such as a hole in the wrapper or an unsatisfactory seam between the overlapping marginal portions of the wrapper) or if the filler of a section is too dense or contains less than the desired quantity of tobacco and/or filter material. .[.If.]. .Iadd.It .Iaddend.is also known to break up rows of closely adjacent rod-shaped articles by removing from the row each second, third, etc. article in order to convert a single row into two or more rows or to stack selected articles in trays or other types of containers. Furthermore, segregation of selected articles from a predetermined path wherein the articles move lengthwise or sideways is often necessary in order to convert a file of articles which move axially into one or more rows of articles which move sideways, or vice versa.
In the majority of presently known machines for the mass-production of cigarettes or like rod-shaped articles, the defective articles are segregated by pneumatic ejecting means. The ejecting means receives electrical or pneumatic signals which are produced by the detector or detectors of a testing unit and are employed to effect the segregation of articles at an ejecting or segregating station having a width which equals or approximates the distance between two neighboring articles. The detector or detectors scan the wrappers, the fillers and/or the heads of articles and produce signals in response to detection of one or more defects. Since a modern cigarette making machine produces up to 70 cigarettes per second, the testing of cigarettes must be carried out at the same speed and, therefore, the intervals for ejection of a defective article which is flanked by two satisfactory articles are extremely short. As a rule, the length of intervals which are allotted for ejection of defective articles in the range of one or more milliseconds. It is very difficult and highly expensive to produce satisfactory pneumatic valves which are capable of responding to electrical or pneumatic signals without any delay or with a delay which permits for segregation of a rapidly advancing article within an interval of a few milliseconds. Delayed opening of valves can result in ejection of satisfactory articles (in addition to or instead of defective articles). If the valve or valves remain open longer than for the interval which is required to move a defective article through a distance corresponding to that between the centers of two neighboring articles, a satisfactory article which follows a defective article is likely to be segregated with such defective article. Furthermore, if the defective articles are ejected by streams of compressed air, it takes a certain amount of time before the air pressure in the conduits for compressed air builds up to a value which is satisfactory for reliable expulsion of the selected article.
Certain recent types of electromagnetic valves are capable of opening and closing with a minimum of delay; however, the useful life of such valves is so short that they must be replaced at very frequent intervals and the valves are so expensive that they contribute excessively to the cost of testing apparatus for cigarettes or the like. Furthermore, since the valves are prone to malfunction after short periods of use, they are likely to cause ejection of satisfactory articles or to permit passage of defective articles during the interval which elapses between the start of malfunction and the detection of faulty operation of a valve. The operating speed of modern cigarette making or like machines being very high, even short-lasting malfunctioning of valves which are supposed to effect segregation of defective articles is likely to result in substantial losses in output or in the production, packing and sale of large quantities of defective products.
It is also known to segregate defective articles by gravity, by centrifugal force or by a combination of such forces with each other and/or with a pneumatically produced force. For example, the articles are advanced along a circular path and are held against the action of gravity and/or centrifugal force by mechanical and/or pneumatic means. The retaining force which acts upon a defective article is terminated in response to detection of a defect. Such methods and apparatus exhibit the drawbacks of the aforediscussed proposals, i.e., it is difficult to terminate the retaining action within a very short interval of time in order to insure that the ejecting force (e.g., gravity or centrifugal force) will act only upon a defective article but will be unable to dislodge a satisfactory article which precedes or follows the defective article.
It can be said that the development of reliable ejecting or segregating devices lags behind the development of machines for the mass-production and testing of plain or filter cigarettes, cigars or cigarillos and filter rod sections.